Crab Farming Techniques: Key Points and Methods Explained

Because of Chinese people's love for crab in recent years, livestock farmers have started farming crabs one after another, and since raising crabs does not take too much time, it is quite satisfactory to farmers.

Techniques for farming crabs in ponds

1. Pond conditions

The flat-legged mud crab requires an adequate water source, convenient water intake and drainage, and good, pollution-free water quality. Choose clay, sandy soil or loamy sand with good aeration, which is favorable for the growth and reproduction of aquatic plants, benthic insects, snails and mussels, water earthworms, and so on. Old ponds must be thoroughly desilted, with the shallowest part at 10cm. Several earthen mounds slightly above the water surface, namely crab islands, can be built in the pond, and aquatic plants can be transplanted onto the islands. The pond should not be too steep, with a slope ratio generally below 1:1.5; otherwise, river crabs easily dig burrows, and it is not conducive to climbing out of the water at night for activity. Artificial caves can also be built.

2. Transplanting aquatic plants

The level of natural river crab yield mainly depends on the amount of aquatic plants and benthic organisms (food organisms) in the water area. Planting aquatic plants well during the farming process is an indispensable technical measure. In addition to providing food for crabs and supplementing vitamins, it is also commonly said that "the size of the crab depends on the aquatic plants." Therefore, for pond farming of river crabs, great effort must be made to plant aquatic plants well. The main types of aquatic plants include duckweed, Azolla, water hyacinth, water lettuce, Hydrilla verticillata, hornwort, Vallisneria, alligator weed, and so on. When transplanting, pay attention to disinfection and pest prevention.

3. Anti-escape facilities

Anti-escape facilities mostly use plastic film, and some use cement boards, depending on individual circumstances.

4. Pond clearing and disinfection

For the swimming crab, generally half a month before releasing the seedlings, quicklime is used to clear and disinfect the pond, at a dosage of 75 kg per mu. On one hand, it can kill harmful organisms; on the other hand, it can improve the pond bottom, increase the calcium ion content in the water body, and promote the molting and growth of river crabs. After filling with water, fertilize promptly to cultivate algae and basic food organisms, and generally maintain transparency at 40-50cm. If tadpoles or frog eggs are found, remove them promptly to avoid competing for food and harming young crabs.

5. Releasing seedlings

For seedling selection, crab seedlings produced in the Yangtze River system are preferred, requiring uniform specifications, complete walking legs, robust physique, active crawling, and no injuries or diseases.

For seedling release and density, pay attention to temperature differences when releasing seedlings. Seedlings purchased from other places cannot be placed directly into the pond. They should first be soaked in water for 2-3 minutes, taken out and left for 10 minutes, and this should be repeated 2-3 times. After the young crabs gradually absorb enough water and adapt to the water temperature, put them into the pond, which can increase the survival rate.

Density: Mostly mixed farming, especially mixed farming of fish, shrimp and crabs, which gives higher economic benefits. The density can be controlled within 1500 crabs per mu, with specifications of 120-150 juvenile crabs. If conditions are poor or shrimp farming is the main focus, the amount of seedlings released can be appropriately reduced.

Techniques for selecting crabs

1. Look

High-quality crabs have a bluish-gray dorsal shell with luster, a white abdomen, golden claws with clumps of yellow hair, bright color, a round and plump navel that protrudes outward, firmly connected limbs in a curved shape, and are large and mature. If the back is yellow, the meat is relatively thin and weak. In addition, if the crab is strong in activity and crawls around everywhere, it is a robust and good crab.

2. Weigh

For crabs that visually meet the appearance requirements, weigh each one by hand. Those that feel heavy are plump crabs. This trick does not apply to river crabs and live sea crabs, because these crabs are often tightly bound.

3. Peel

Peel open the crab's navel cover. If there is a lot of crab roe inside the shell, neat and condensed into shape, then this crab is a good crab.

4. Pull

If purchasing dead sea crabs, observe the crab legs. If they are complete and intact, and a gentle pull on the crab legs shows weak elasticity, it indicates fresh sea crabs. If the sea crab is not fresh, a gentle pull on the crab legs not only shows no weak elasticity, but the crab legs easily break off.

5. Smell

If a fishy odor is smelled from sea crabs, it indicates that the sea crabs have spoiled and deteriorated and can no longer be eaten. Eating spoiled and deteriorated sea crabs can easily cause food poisoning.

The best time to eat crabs

Around the ninth lunar month, female crabs have mature gonads and plump meat; after the tenth lunar month, male crabs have mature gonads and plump meat, so they should be eaten at the right time.

Methods of catching crabs

1. Catching crabs with crab fences

A crab fence is a simple blocking-type fence-and-screen crab-catching tool woven from bamboo. Its structure uses thin bamboo poles or thick reeds woven into a fence. In favorable sections of river ports and lake branches with flowing water, stakes are driven and fences are set according to a pre-planned formation. The lower end of the fence is inserted into the water bottom, and the upper end extends above the water surface. The entire fence is regularly curved. At the upper end of the fence, some drum-shaped crab baskets are hung. At the bottom of the basket there is an entrance for river crabs and a funnel-shaped reverse barb, the upper part has a cover, and the middle is the gathering place for river crabs. When river crabs migrate downstream through the waterway into the sea, they are intercepted by the crab fence placed across the water surface. After being blocked, they climb along the fence or drill into the crab baskets. When harvesting, use a dip net to catch the crabs on the fence or in the crab baskets.

2. Catching crabs with crab trawl nets

The fiddler crab crab trawl is a wingless single-bag trawl fishing gear, composed of a rectangular net folded into a pocket and a shallow bag net. The crab trawl is driven by a single boat. On one side of the boat, a bamboo pole for supporting the net extends from the bow and stern respectively, and 8-12 Qiu nets are tied. At this time, river crabs rush into the net from the net mouth. After entering the net, some river crabs crawl forward along the back of the net, are blocked by the intercepting net, and then turn into the side net. The other part remains in the net pocket. Lift the net once every 1 hour and move to another place, and at the same time pour out the river crabs from the net pocket and bag net.

The crab trawl is one of the main methods of catching crabs in the Yangtze River, and this fishing gear is also used in some lakes. From Anqing in Anhui to the Yangtze River estuary in Shanghai, such as the coastal areas of Chongming and Hengsha, the Huangpu River and Dianshan Lake in Shanghai, and Hongze Lake, Gaoyou Lake, Baoying Lake, and other places in Jiangsu, this fishing method is commonly used. It has the characteristics of small fishing gear, easy operation, and full use of water flow dynamics, and is an effective tool for catching natural river crabs. However, there must be no sunken boats, reefs or quicksand in the operation area; encountering them will damage the trawl.

Taboos for eating crabs

Crabs should not be eaten with sweet potato, pumpkin, honey, pear, pomegranate, tomato, muskmelon, peanut, snail, celery, persimmon, rabbit meat, or Schizonepeta; eating crabs should not be accompanied by cold drinks, which can cause diarrhea.

Really, during crab-eating season, after eating crabs or while eating crabs, do not casually eat them together with other foods; otherwise, not only will you fail to happily enjoy the food, but you may also have an unpleasant dining experience because of carelessness while eating crabs.